<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8" />
        <!-- 内嵌式引入
            1.在head标签中用一对javascript标签，嵌入js代码
            2.type属性可以不写
        -->
        <script type="text/javascript">
            function fun1(){
                alert("hello world!")
            }
        </script>
    </head>
    <body>
        <input type="button" value="点击我" onclick="fun1()"/>
    </body>
</html>